getting Fit

Question
horse question
Question:  I have a 12-year-old thoroughbred that I bought 3 months ago. He is an ex-racehorse, and he raced until he was 6. His previous owner had pastured him for 3 years. Before he was pastured, he was a good show horse, he did some dressage and jumped 4' courses. I would like to get him back into jumping eventually. First, I have a few problems. I have only ridden him a few times since I bought him. I was trying to build a relationship on the ground before riding. The problem I have when riding is that he is not focused on me. He likes to look around, and sometimes he will get mad and start rearing and bucking when I do not allow him to look around. I started riding him in a large arena, but switched over to a round pen because he does better in there. He is starting to pay attention better in the round pen but I would like to ride him in the big arena. If I ride him in the round pen and he learns to listen to me after a while will he also listen to me in the arena? How do I go about getting him to listen to me in the arena? Also, since he has been pastured for 3 years he is out of shape. He does not have much muscle on his body. How do I go about getting him in shape correctly? When I ride I always lounge him first for about 15 minutes to get him warmed up, then I ride him for 10 minutes.
How long will it take to get him in shape before I can start jumping him?
Thank you
Erin  

Answer
First of all I have to tell you that I don't have much experiance with using a round pen, but I do know a few things.  Also two things that will help you a lot with this problem is to ask for help from a fellow rider/trainer or find a trainer to work with you, also The Monty Roberts books help greatly.  The books by Monty Roberts use the round pen a lot and also the book is very imformative on the signs a horse makes when he is listening to you, for example; "chewing" motion of their mouth, a lowered head and neck, and the inside ear tilted towards you.  As for riding him in a big arena; circles are the best way to get their attention and transitions are helpful if your horse starts to get headstrong.  To help get your horse in shape trotting is the best thing to do.  Trotting requires for the horse to use more of their muscles than any other gait.  Longing is a good idea, especially if he doesn't always listen to you.  When you ride try to ride for 30 minutes to an hour, nothing grueling though, just a lot of walking and trotting and some cantering.  Also, if you have the land to do it, take him for long walks, like around a pasture or on a trail.  As far as jumping him, that is your decision, whenever you think that he can handle it.  To start you can set up ground poles or cavelleti then slowly progress higher when you think he is ready.
Godd luck and feel free to write to me again if you have any more questions.